Fuel supply control for airatomizing oil burners



4 Sheets-Sheet l IMVENToRs IIAMYETW ma H. F. TAPP ET AL .laid-.link NIITL FUEL SUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS May 5, 1953Original Filed Sept. 2, 1950 May 5, 1953 H. F. TAPP ErAL 2,637,375

FUEL SUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS Original Filed Sept.2, 1950 4 sheets-sheet 2 ATTORNEYS May 5, 1953 H. F. TAPP ETAL FUELSUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS` 4 Sheets-Sheet 3 OriginalFiled Sept. 2, 1950 www5 m Wn m ww m wr. m IIE u. A Y' mm an m s N.. aS/bv a a. Q NN N51 .inn Q NN WNW i V. Q Nm. NNIT. N $4 s, QN O A-w......4,......w Q @wh .wh Illlqlldllrnl "Il" N3 1 ..wm .N U m L ,i vau $1 @NN u l l l n 1r XWNN fus. NNY RN May 5, 1953 H. F. TAPP ETAL FUELSUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS Original Filed Sept. 2 19504 Sheets-Sheet 4 INvl-:NToR s HARRY!! 7h Alm Patented May 5, 1953 FUELSUPPLY CONTROL FOR AIR- ATOMIZING OIL BURNERS Harry F. Tapp, Longmeadow,and Richard M. Cochrane, West Springfield, Mass., assignors to Gilbert &Barker Manufacturing Company, West Springfield, Mass., a corporation ofMassachusetts Original application September 2, 1950, Serial No.

182,952. Divided and this application September 19, 1951, Serial No.247,272

(Cl. S-42.2)

2 Claims. 1

This invention relates to an improved oil burner oi the so-calledair-atomizing type.

This application is a division of our application Serial No. 182,952,filed September 2, 1950, and entitled Air-Atomizing Oil Burner.

. The invention has Lfor its general object the provision of a burner,which will burn fuel oils of various grades, including heavier grades,such as No. 5 fuel oil, for example, under conditions that can becontrolled with precisen to yield efficient and clean combustion, andwhich may be used to fire very small furnaces, such for example as haveheretofore been fired by pot type burners, and even the small re boxesof stoves and kitchen ranges.

The burner utilizes an air-atomizing type of nozzle to enable low firingrates to be secured with nozzle passages and orifices, which are largeenough to avoid clogging, and to enable eiiective atomization to beenected at relatively low pressures. Oil, primary air and secondary airare respectively supplied by a pump, compressor and fan, all driven byan electric motor, usually under automatic thermostat control and therate of flow of oil and primary and secondary air to the nozzle isregulable with precision as is the pressure of the oil and primary airsupply, so that combustion conditions can be laccurately controlled. y

'The invention has for other objects to provide in a burner featuresofconstruction which enable manufacture at relatively low cost and at vthesame time provide for efficient and controlled` combustion, and toprovide features involving improved construction and arrangement ofparts that provide for convenience of assembly and also of disassembly,when required for easy servicing in the eld. v

These objects Willbest be understood from the detailed description ofone illustrative example of the inventionin the accompanying drawings,in which:

Figs. l and 2 are small scale elevational views showing opposite sidesof an oil burner embodying the invention; .Y I

.-Fig. 3 is a rear elevational view of the burner; Fig. 4 is a sectionalelevational View, taken on the line 4--4 of Fig. 3 and drawn to a largerscale;

Fig. 5 is a fragmentary cross-sectional view taken on the line 5-5 ofFig. 4;

Fig. 6 is an enlarged fragmentary sectional view taken on the line 6--6of Fig. 4, showing thel atomizing lnozzle and` the supplyconduits foroil and primary air;

Fig. 7 is an enlarged cross sectional view taken on the line 'I-l ofFig. 6;

Fig. 8 is a sectional plan view taken on the line 8-8 of Fig. 1;

Fig. 9 is a full-size fragmentary sectional plan view taken on the line9-9 of Fig. 4;

Fig. 10 is a cross-sectional view taken on the line Ili-IU of Fig. 9;

Fig. l1 is a cross-sectional view taken on the line H-H of Fig. 8;

Fig. l2 is a fragmentary sectional elevational view taken on the lineI2|2 of Fig. 3;

Figs. 13, 14, 15, 16 and 17 are cross-sectional Views taken on the linesl3-l3, lli-I4, |5-I5, lG-IB and ll-I'l of Fig. 12; and

Fig. 18 is a cross-sectional view taken on the line I8--I8of Fig. 6.

Referring t0 these drawings: the burner includes a central casing (Fig.1), designated generally as l and affording in its lower portion ahousing for the fan 2, which supplies secondary air to the burner. Thiscasing, as shown in Figs. 1, 2, 3 and 4, is made up of two sections 3and 4, which are so constructed that they may be made by die casting.The larger section 3 has a curved bottom wall 5, forming part of thevolute for the fan, two at parallel upstanding side walls 6 and 'l withrelatively narrow rectangular upward extensions 8 and 9, respectively,which bulge voutwardly slightly, and a front wall I6 which is tangentialto the end of larger radius of the volute wall 5 and which upstands atright angles to the side walls 6 and I and their respective extensions 8and 9. The other end of the curved wall 5 terminates in a horizontalplane passing through the axis of revolution of fan 2. That portion ofeach side wall 6 and '1, which is disposed below said plane, has acurved margin integrally connected to the curved wall 5. Each side wallis further bounded by a short horizontal edge, disposed in said planeand extending inwardly a short distance from the end of smaller radiusof Wall 5; a curved edge, which is a arc concentric with the axis of fan2 and extending from said horizontal edge; a horizontal edge tangent tothe upper end of the curved edge and which is substantiallyv equal tothe radius of the fan; a vertical edge forming the inner edge ofextension 8 or 9, a horizontal edge forming the top of such extensionand a vertical edge united to the front wall l0. The smaller section 4has a curved Wall LI (Figs. l and 4), which extends from said planeandthelast-named end of wall 5 upwardly, over and across toward wall l0and completes the volute of the fan housing; integral, spaced, sidewalls I2 and I3 (Figs. 1, 2 and 8); a connecting end or rear wall I4,which parallels the front wall I9; and a narrow top wall I5. The sidewalls I2 and 1.3 serve as continuations of the side walls and 1, andtheir extensions 8 and 9, respectively, and each has a short radial andhorizontal edge; a curved edge; and Va longer horizontal edge to restupon and abut the corresponding edges of section 3, together with avertical edge to abut the rear edge of the exten.- sions 8 or 9, as thecase may be, .of the ,adjacent side Wall. The sections 3 and k4l areheld together by two screws I5 which pass one through side wall t andone through side wall 'I and thread into the wall II.

The front and rear walls .Iii A and I4 of the .casing (Figs. 4 and 8),have coaxial cylindrical openings therein. In the opening in wall I0 therear end of an air supply tube I6 is suitably fixed as indicated in Fig.8. rThe opening in wall I4 is closed fby a `circular -disk i1, suitably-xed to such wall, as by screws I8 (Fig. 4). This casing 1 is supported`from the floor -i-n any suitable way,

as by a short standard I9 (Fig-s. 1 and 4), iixed at its upper end inthe .lower front part of section 3 of the casing and adjustably securedat its lower end in the cross -bar portion 4of a U-shaped foot piece2li, which rests on the door. rThe uppcr end of the casing I lis closedi-n any suitable way, as in the example shown, by the bottom wall 2I ofa -box 22, which houses lcertain `electrical equipment as will laterappear and which has two downwardly extending parts 23 overlapping theside walls of the casing and secured by screws 23', one to side wall lI2`and the other to side wall 13. The inner end of wall -l-l (Fig. 4) ofthe casing section 4 is 'spaced from w-all I0 to form the outlet 24 ofthe fan, which outlet communicates with the xupper portion -of theinterior of lcasing I and with air tube IAE. The side walls 6 and 1 lofthe casing fhave lar-ge circular openings therein, that 'on wall 6 (Fig.4") being larger than -the outside dia-meter of fan rotor 2 and that inwall l1 (Figs. 3 and '12) rfor-ming the inlet 'to the ian housing. vTheopening in wall 6 (Figs. 2, 3 and 4) is closed by ythe end flange 25 ofan electric motor 26, which kdrives the fan I2 and an air compressor andoil pump to be later described. Flange '25 is secured :by Iscrews 21 towall 6. The motor'has its drive shaft `28 (Fig. 3) extending intovcasing I and secured -in `the hollow end of a stud 28', nxed to the'hub of fan 2, as indicated. The open-ing in wall 1 (Figs. 3 and 12)forms the inlet to the flan. A -deector 29 Aof rvfrustoconical shape'has an louter annular flange, which rest-s in a -fsea-t in side wall 1and is clamped between -t-he latter and an annular ring 3U by screws 3|.This ring 38 Ais integrally connected by -a series of horizontal arms 32-to a circular end plate 3-3 of the air compressor 'and serves tosupport both 4the compressor and the oil pump. There is a space betweenthe plate 33 and Iring 35 for the admission of air -to the deflector 29which 'directs the air axially -to fan rotor v2. A shield, comprising aplurality of -wire rings 34, kmounted in axially spaced relation in the'gap between the ring and end plate, is provided, and these rings aresuitably secured to the arms 32.

The air compressor (Fig. 12) includes a central body 35 clamped betweenthe end plate 33 andan end plate 35 fby screws 31. The body 35 has -acylindrical chamber 38 (Fig. 17) extending tlnlough -it and locatedeccentrically thereof.

4 In this chamber 38 is a rotor 39 having a plurality ofangularly-spaced radially-slidable vanes 40, the inner ends of whichride on rings 4I, disposed one in each of two recesses 42 `formed in theends of the rotor. The chamber '38 may have a liner 43 of suitableoil-impregnated material. An O-ring 44 (Fig. 12) is mounted in a.circular groove in each end plate 33 and 36 to press against 'theadjacent end face of body 35. These rings 44 prevent leakage between theend plates and'body vof the compressor. The rotor `3.9 is ixed asindicated to a drive shaft 45, which is rotatably mounted in suitablebearings, one

r-i-n each of the end plates, and projects beyond the end plate '33 andinto the fan housing where it is connected by .a suitable exiblecoupling 46 (Fig. 3.) @to the outer end of the described stud 28 andthus to motor shaft 28. The inlet and outlet ports of the compressor areshown in Fig. 17 at 41 and 48, respectively. They are arcuate groovesformed in the inner face of the end plate 316. The outlet port v48 isconnected by a horizontal passage 49 (Fig. 16) to two radial passages 50and 5I Aformed in end plate 36. The outer end of 'passage 51 is normallyvclosed by fa. plug 52 and is ladapted for connection to a pressuregauge vwhen the plug is removed. The outer end of passage 50 is ladaptedfor connection by a pipe 53 to the vprimary air supply passage of theatomizing nozzle as will later be described in detail. The inlet port 41is connected to one end of a passage 54 which extends horizontallythrough end plate 36 (Fig. 16) and part way into a boss 55 (Fig. 14)formed on an abut-ting plate 56, which as shown in Fig. V12 is Isecu-redby screws 51 to end plate 36. Plate '56 has projecting from it an innerboss v58 housing the oil pump and an outer annular marginal rim 5S. Theboss 55 described merges 'with boss 58 and has radial holes jyconnecting -hole 54 to the space between the boss 5B and flange 59.

A m-u-iller -of the labyrinth type is provided on the intake side of thecompressor. The space 'between the described hub 58 and 'rim 59 (Fig.14) is subdivided Jby a series of angularly-spaced baiiles, 61, 62, AE3,64, vand 66 which extend radially from the hub to 'the lrim and whichproject longitudinally -from plate 5'6 to the same 'extent as rim 53 andboss 58 (see Fig. '12). The baffles 62 and 65 (Fig. 14) are formed, onradial bosses 51 and 687, respectively, on plate 56. A thin pla-te 59(Fig. 71,2), having `on its inner face a layer of vsuitablesounddeadening material '10 abuts the outer end races of the rim 59, the'boss 58 land all the baffles and is secured by four screws 1I (Fig.14). 'lhe bailies thus subdivide the 'space between rim 59 'and hub 58and between plates 55 and A69 winto a series of compartments 12, 13, 14,15, 16, and l1'1. The baffles 62 and A63 and the baiiles '65 and 86 havea plurality of notches `18 in their outer end faces but the bames 6I and64 are imperforate. Air inlet openings 19 (Fig. 14) are provided inplate 69, to admit air tothe chambers 1'2 and 15 on opposite 'sides ofthe vimperforate baille GI. Air from chamber 12 follows a clockwisepath, passing through the open-ings t18 in baiiie 62 into chamber 13,through the openings 18 vin 'baille '63 into chamber 14 'and thencethrough the right hand radial hole 60 into horizontal hole 54 and thenceinto the inlet port -60 into the horizontal hole 54 and thence to theinlet port 41 of the air compressor.

The oil pump is shown in Figs. 12 and 15. It is of the variable-capacitytype and is mounted in a cylindrical recess 80 in the boss 58, whichrecess is coaxial with shaft 45 and extends from its rear face towardbut not through the front face ofzthe boss. The end plate 36 ofthe aircompressor has a portion 58' of its central and'bearing-containing hubentering the aforesaid recess to close it on the air compressor side andthe joint between the abutting faces of this boss and hub is suitablysealed as indicated. Into this recess is pressed a ring 8|, havingcentrallyin its inner face two grooves 82 and 83 (Fig. 15), which areseparated by two diametrically opposed lands and which form the inletand outlet ports of the oil pump. A cup-shaped rotor 84, rotatably tswithin ring 8| and between the end walls of the recess 80.' This rotorhas a slot of non-circular shape in its vend wall to receive a key 85which is of similar shape (see also Fig. 16) and is formed on the outerend of shaft 45. Two cylinderforming holes are provided through theannular part f the rotor in diametrically opposed relation to receivethe ends of a piston 86. This piston is fixed centrally between its endsin a cylindrical piece 81 which ts within the cup-shaped rotor and maybe moved to various positions of eccentricity relatively thereto. Thepiece-81 has l a groove in its outer face to receive a-slide 08. Thelatter has a hole therein to receive a pin 89 eccentrically located onthe inner end of a shaft 90 which is mounted in hub 58 and a smaller hub9|, integrally connected thereto, to turn about an axis eccentric toshaft 45. Suitably fixed as by welding to the outer end of shaft 90, isa plate 93, having a curved slot therein, and this plate may be held invarious positions of angular adjustment by a screw 34 which passesthrough the slot and threads into boss 3|. By moving shaft 90 as by atool inserted in the hexagonal depression 92 in the end of shaft 90 thepin 89 may be moved to vary the radial position of the piston 86 andthus the capacity of the pump. A eu-p-shaped pressed-metal cover 95conceals the oil-pumpadjusting means described and is held to' a lug 96on boss 9| by a screw 91. The oilk inlet for the pump is formed in thedescribed boss 58 (Figi 15). It includes a radial passage 98, having acounterbore, in which is received a filtering screen 99 having an openinner end surrounded by a flange that is pressed against a seat-in thecounterbore by means of a spring |00, acting against a plug |0I,threaded in and closing the cuter end of the counterbore. A passage |02connects this counterbore to an inlet |03, into which is threaded oneend of suction pipe |04 adapted for connection at its other end to anoil supply tank (not shown). The outlet port 83 is connected to a radialpassage |05 having a counterbore, the threaded outer end of which isnormally closed by a Aplug |06 that is removable to enable attachment ofa pressure gauge, when desired. A diagonal passage |01 connects thelast-named counterbore to an outlet |08 into which is threaded a pipe|09 for supplying oil to the nozzle of the burner.

` It will be noted from Fig. 12 that the left hand bearing ||0 of theair compressor adjoins the oil pump and is positioned to receive some ofthe pumped fuel oil and utilize such oil for lubricating purposes. Asealing ring is provided on the right hand side of bearing |0 to tightlyseal the bearing and prevent oil from the pump entering the compressorand to prevent air from the compressor from reaching the oil pump. Theoil pump is used as a metering pump as well as a transfer pump to drawfuel from a low level supply tank and it is important for the latterpurposeto provide the seal described to prevent loss of suction.Referring next to Figs. 4 and 8, thedisk I1'is secured, as by screws||2, to a casting |I3. The latter supports' one end of a tube II4, whichextends coaxially through the described secondary air tube I6 andterminates near the forward end of such tube with an atomizing nozzle,the body and cap of which are designated l5 andA I9- respectively. The'casting |I3 has a lateral extension ||1 (Fig. 8) which extendsinto andlls a slot in the side Wall I3 of the casing section 4 (see also Figs. land 3) andinto which the described air and oil pipes 53 and |09 arescrewed. These pipes have unions |B and I I9, respectively, which arelocated near member ||1 and which can be disconnected whenever it isdesired to remove the assembly comprising disk I1, members 3 and |I1,together with the tube |I4 and the atomizing nozzle and other partsconnected thereto, as will be later described in detail.

Referring next to Fig. 9, it will be seen that the member I I3 and itslateral extension ||1 have radial passages |20 and |2| which at theirouter ends respectively connect with the air and oil supply pipes 53 and|09 and which at their inner ends respectively connect with annularchambers |24 and |25 formed in member ||3 coaxially of tube I4. Withinthe tube I4, which at its outer end is screwed into member |I3, is anoil supply tube |26. This tube carries an O-ring |21, which Ipartitionsthe chambers |24 and |25. lTube |26 has fixed thereon a snap ring |28which together with a shoulder |29 confine the O-ring to an axialposition such as is eifective to seal the oil chamber |25 from the airchamber |24. The air chamber |24 connects with the annular space betweentubes ||4 and |28 and the oilA chamber |25 connects with the spacewithin tube |26.

Referring next to Fig. 6, the forward end of air tube I I4 iscounterbored to receive and closelyt a disk |30. The nozzle body ||5 hasa threaded portion I3 I, which screws into the forward end of tube I I4and clamps the disk |30 between its end wall and the end Wall of thecounterborej. This disk has an integral and rearwardly extending hwb|32, which tightly fits vinto the forward end of oil tube |23 and whichhas inside the tube -a valve seat |33. The latter is adapted to beengaged by a valve |34 on the end of a rod|35 located within tube |25and slidably supported from the inner periphery of the tube in anysuitable way as by the radial projections |36 on the rod. An oil passage|31 extends. axially through the disk |30, hub |32 and seat |33 toreceiveoil from tube |25, when valve |34 is moved to the left away fromits seat. This oil passage |31 registers with a central passage |38 inthe nozzle body ||5. The disk |30 also has in its-.forward face anannular groove |39 and a plurality of holes |40 which extend from thebottom of the groove to the rear face of the disk and there corn.-municate with the annular space between tube |4 and pipe |26 to receiveprimary air. The nozzle body ||5 has extending longitudinallytherethrough a plurality of passages `|4I arranged in angularly-spacedrelation about the central oil passage |38. These air passages |4|communicate at their rear ends with annular groove |39 and at theirforward ends with Yan annular cham,- ber |42 formed within cap ||6 andthe forward acens 7 cud |48 or the nozzle bodywhich end is of reduceddiameter. `The cap H is threaded onto a part of the nozzle body and itsfront wall a central -oriiiee 445 which rlea-ds from a conical res cessIl-S, Vformed in the inner face of the front wall, to the outer face ofsuch wall. The iront end xof the nozzle ypart M3 is counterbored toreceiye the inner flanged end .of a cylindrical piece llt!whiclrterminates with a frustonconical Aend I. projecting into theconical i/ecess IM in spaced relation 'therewith to form an annularWhirl chamber IAG .which converges to :the `oriee |45, The .part Ml hasan axial oil passage |.5 which at one end .mmunicates with oil lpassage|33 and which extends .closely adjacent to .but stops yshort of 'thefrontend of part JM. Here, the passage communicates with the inner endsci a plof rality of holes ll which .extend radially outward tothe outerperiphery or part 1.41. .Encompassins the cylindrical part Jil?! is anannular .rips |52; which is pressed into and held in abutment with theouter .end face .of :the part 4.4.3 by :the can 14.6 and which in turnholds the .in-.nerfflaneed .end of member .M1-inns seat :in thecountcrbore.. This ring |52 'has in its viront :face an annu-.lar.groove |53 closed fot the .iron-t by .cap .i l .and a plurality of.singularly spaced slots .|154 .located taneentiolly of the .groove |53ariel .connecting .et their outer .ends with the air chamber |42.. Theprimary air enters taugentially into .tl-.1e chamber |53 at a Q.

plurality of angularlyfsoaced locations ,and meets the .oil streams.issuing .radially from .holes |51, intercepting these oil streams .atright anales and eiecting an intimate mixture of fuel and air. Thismixture, whirling Lin the chamber |53, advancesiinto the con-ical whirlchamber |49 where it is caused to whirl at rapidly 'increasing velocityas it advances to the outlet oriiiee |45. This rapidly-rotating streamof mixed fuel and air is confined peripherally .until it emerges fromthe orifice V45, :where being `released `from peripheral confinement itflies apart by centrifugal force into a tegel-ilse spray.

Referring again to Fig.. 9, it will be noted :that the members H .and H3have flat annular faces. between which is clon-ined the marginal portionof a circular diaphragm |55. The 'latter is een.. trall'y perforated toreceive the threaded hub of `a plate .il-5.6, which abuis .one face ofthe diaphragm 4.5.5. An ,annular ring |51, engaging the opposite .faceof the diaphragm, receives the threaded hub of plate :|56 and 'a 'mit|58. threaded on `such hub .draws the yring and plate Vtogether to.clamp the diaphragm therebetween.

The valve rod |35, above described, is xed at rear end as indicated inthe hub .of plate 1156;. An `O-ring i5@ en `the lvalve rod preventsleakage ofv oil from chamber |25 into Vthe chamber |613 which is loi-medin member |3 on the right side ofthe diaphragm. vCharn'lzier |56 isconnectedto air passage |253 by a passage |6| (see also Fig. 10'). Thechamber |62 onthe'cther side of lthe diaphragm is connected Jto `theatmosphere by ahole |63, Jformed in a plug |64, threaded into andclosing the outer end of an axial passage vH in `disl; I7, which passagecommunicates with chamber |62. A spring |6 acting between plug `64 andplate 15E `tends to move valve rod |35 Ito theright and hold 4valve |34-to seat |33, thus preventing oil from entering rthe nozzle untilsulficien't air pressure has been built up by -the vcoinpressor to forcediaphragm |55 to the left against the force ofthe spring |6 to open thevalve. The pressure, at which valve |34 opens, is variable by adjustmentof screw |54, which is accessible from outside the burner casing as inRig. 3 for the purpose.

The air `pressure is regulated by an adjustable relief valve |81 shownin Fig. 9. This yvalve is mounted for yatrial sliding movement in thecounterbored Iouter end of a vpassage |68, formed in the lextension IH`sind para-Heling air passage |20. The inner end of passage |68intersects 1the passage |5| and receives air therefrom A(see also Fig.lo). The seat for valve i|61 is the shoulder at the intersection ofpassage |68 with its counterbore. The vvalve Vis held to this lseat 'bya spring |83, having a seat 'ina ping HB which is threaded into andcloses .the outer end of the counterbore. A yent passage lsee ralsoFig'. 10) connects the Lcounterbore vat a point :between the -valye seatand plug y|1|| with the exterior of extension IH, opening into the airchamber -i-n the upper part of .the fan housing. The Yforce exerted byspring IB@ .on 'valve |61 is variable by turning screw plug HB, which isaccessible lfrom outside the burner Casing, as will be clear from Fig.1, and enables the air pressure to :be readily adjusted. As at presentcontemplated, :the burner may operate with an air 'pressure betweenl'l/z 4and i p. s. i.

,Secondary air is .supplied by Vthe fan I.through tubo 6. as will .beclear from Fiss. e and .8, Fixed to lthe tube vit at a point.intermediate its ends. as by :screws |72, is an annular :ri-ng |13,baume projecting .inwardly therefrom a .circular series of helical vanosA| i4. The :inner edges .of these venes engage the outer peripheral wallyof .a cylindrical tube |i5 and supi-Jort it in coaxial relation Awithtube Hi.. @The .front enel of tube U15 .is onen .and .terminatesadjacent .slieiitly to .the rear o! the atoiniailie nozzlehe rear end.of tube |15 is .closed by a :plus |16. which is secured. to the tube osindicated which has a :rounded rear end to divert the air stream issuingfrom the out let .2A of the the. .polar passage -lr'il be. tween lthetubes l E .and |75, As will be clear Yfrom Fie. 11 successive helicalblades il! .the series overlap .so that ,all ,air vtravolti-igtlno-ugl'i the l,annular passage |751 is engaged by the blades andCaused vto whirl as it .mo-.Ves forward .in such pas sage. The whirlingair stream, emerging from passage |11 -isdeilectedtoward theceutralsileam oi fuel and .airJ which is emitted .from the .nozzleorifice 1.45 by Vmeans of .a frusto conical air di rector HB .on theoutlet .end .of :tube A| .6.. Substao tially .all the secondary .airiswhirled as described. There is a Single .small vent passage .|19 (Fisceands) formed :in plus .il .for .the purpose of preventing .the formationofc vacuum .in the .interior of tube ,115. Except for the insignificant.amount of air enter-iris .tube ilo .through this yent pas.- sae'e, allthe .secondary air Supplied by fan 3 .is whirled. The plus .|15 has aControl .Opening therethrough which receives .and closely fits thedescribed .nozzle-.carrying tube |14. .A set screw |89., threaded in theplus |.f'|6ho1.ds tube H4 in place- Thus, the `varices ilisuzoport tube|15. the conduit .for secondary airond the oil conduit together with theignition electrodes.

The ignition electrodes are .shown .at 18| .(Fies.. e1, 8 11),. They aremounted in insulators |82 which in turn .extend .through .holes in plus|76. Each insulator `is held in place by a set screw 18.3, .threaded inplus .H6 and acting against a @am Asplit sleeve |34 (Fig. 5), which.surrounds the electrodes.. .On theroar'erid .of .each electrode (ses. i.and .si is a mete-,1 seminaires .which progressively .increases indiaeooter rearwardly to form a cam. These cam terminals .|85 areengaged. one by each of two serios-pressed .mee

taille Dllmgors u|86 (Fig. 4j) mounted .in 4an 111511 lator |81, whichis xed in bottom wall of casing 2| and carries the high tensionterminals of an ignition transformer |88, which is mounted in the fronthalf of the described box 22.

each of the spring-pressed plungers |36. It will be clear that, when thedisk is unfastened and pulled rearwardly it will carry with it theassem- These terminals suitably connect electrically, one with bly oftubes for primary air and oil and the ignition electrodes and that theconnection between the transformer and electrodes will be broken beforethe electrodes are withdrawn from the tube IB. This entire assembly canreadily be removed from tube I6 for inspection, adjustment or re'- pairand may as readily be replaced in the tube. As this assembly is replacedthe cam terminals I 85 engage and .force upwardly the spring-pressedplungers |86, thus remaking the electrical connection between the hightension terminals of the transformer and the ignition electrodes. Theseelectrodes are suitably located so as to produce an arc between them toignite the spray of fuel mixture.r Preferably, the tips of theelectrodes are located above and out of the path of the fuel spray andthe arc produced between these tips is blown into such path by thesecondary air.

The rate of flow of the secondary air stream is varied by means of adamper IBB (Fig. 4), which is pivotally mounted at its lower end on arod |90, suitably fixed at its ends in the side walls S and l andextending therebetween. This damper may be swung toward or away from thefan rotor 2 in order to vary the effective area of the outlet 24 of thefan. Conveniently, the damper may be moved by means of a screw |9|having a knurled head |92, which is located outside the housing and bymeans of which the screw may be turned.

The front wall lll of the fan housing has an opening, through which theshank of screw |9| passes. The peripheral' wall of .this opening closelyts a ball-like part |93 on the shank of the screw. On the outer face ofwall lil is a rounded part-cylindrical projection |94 which is engagedby an end face of the knurled head |92. A coil spring |95, actingbetween the inner face of wall It and a washer |95 fixed to the screw.draws the head |52 against the rounded part |94. The screw is thus ableto swing up and down about ball |33 as a fulcrum, as may be necessary asthe screw lili is turned. The screw is threaded into a nut |3l, held inplace by curved prongs |98, formed on the damper, in a manner such as toallow the nut to turn relatively to the damper as required, when thedamper is moved in and out by turning the screw.

The described box 2.2 may as indicated in Fig. 4, contain, in its rearcompartment, some of the controls for the burner, such as the relay |99,the thermal safety switch 200 and the reset butu ton 28| for the safetyswitch. This button is accessible through a hole 202 in the rear wall ofcasing 22 (see also Fig. 3). wires enter this casing through an opening203 (Fig. 2) and a cable 2M (Figs. 2 and 3) extends from controls insidethe casing to the motor 26.

In operation, when the motor 2B is started, usually automatically, on ademand for heat, as by the well known thermostat control, the fan, aircompressor and oil pump are simultaneously started up and driven but theemission of oil from the nozzle is delayed until conditions of air flowand pressure, suitable for good combustion, are established. The valve|35. prevents oil from entering the nozzle until the primary air hasbeen placed. under sufiicient pressure to overcome the force of spring866 and move the diaphragm |55 1o to open the valve. This helps inavoiding smoke during the starting interval of operation of the burner.Flow of primary air through the nozzle passages and out through thenozzle orifice and flow of secondary air in the annular passage Ill andout through the open end of tube i@ will be established before valve|365 opens. Hence, when the valve does open, the oil issuing in radialjets through passages l5| of the nozzle will be met and impinged by jetsof primary air issuing tangentially through passages ifl into thechamber |53. In this chamber, the oil and air will be mixed and themixture will be whirled at considerable velocity. The whirling oil andair mixture advances into the whirl chamber |69, where its velocityrapidly increases as it approaches the outlet orifice |45. As thisrapidly-rotating oil and air mixture emerges from the orifice and isfreed from peripheral confinement, it iiies apart by centrifugal forceinto a cone-like spray of nely divided particles and fog-like form. Thespray is met by a stream of secondary air, whirled by the turbulatorvanes HM, and the mixture is ignited by a spark produced between theelecf trodes li. rlhe whirling of the secondary air produces a short andwide llame having much the shape of an umbrella, adapting it for use insmall fire boxes. Combustion continues until the demand for heat issatisfied, when the motor 25 is stopped. As the motor decreases inspeed, the pressure of the primary air will soon drop sufficiently toenable valve |34 to be closed by spring |66. y The oil flow is veryquickly and sharply cut oir from the nozzle, preventing any dribblingtherefrom. However, flow of primary air con? tinues which purges thenozzle. The early closure of the oil valve, well ahead of the cessationof air flow, helps in avoiding smoke during the stop-ping interval 'ofoperation of the burner.

Itis to be noted that the conditions contributiing to combustion may allbe accurately con# trolled. The oil pump is a metering pump, as well asa transfer pump, and provides for oil flow at a definite rate, which isvariable by adjustment of the member Sil. The desired rate of oil flow,once obtained by this adjustment, will be maintained. The supply ofprimary air from the positively-acting compressor is at a constant ratebut this rate and the pressure of the primary air are adjustable byturning screw HEB, which controls the force of spring |69v which holdsvalve |61 closed. By by-passing some of the air, forced by thecompressor into the passages iZ, ll, |63', and lli, the rate of flow ofprimary air and the pressure thereof may be varied. The air pressure atwhich the oil Valve i3d will open is regulable by turning the screw IMwhich varies the force of the spring ifi@ that holds the oil valveclosed. The pressure of spring it@ must, of course, be somewhat lessthan the air pressure secured by adjustment of screw |13. The rate offlow of secondary air is adjustable by the swinging shut# ter |89 in thefan housing. .All'theadjustments are readily accessible from outside theburner housing, except for the adjustment which varies the rate of oilflow, and for considerations of safety it has been thought best toconceal this oil-flow adjustment from unskilled persons who possiblymight tamper with it. However, to the service man the adjustment isreadily accessible by removing the cover S5, after the one screw diwhich holds it in place has been removed.

As one illustrative example, to illustrate how small a nre the burnerwill produce, a burner constructed according to the disclosuresatisfactorily fired a combustion chamber seven inches long, five incheswide and ten inches high, using oil at the rate of .3 gallon per hourand at a pressure slightly less than 2.5 p. s. i., and primary air at apressure of 2.5 p. s. i. The motor used was rated at one twentieth of ahorse power.

The construction of the housing l in two sectionsl enables thesesections to be manufactured economically by die casting and alsofacilitates the assembly of parts within the fan housing and alsoservicing of the fan. With the upper section 4 removed and the motor 26bolted to the lower section 3, the fan rotor 2 may be placed on shaft 28in proper position and secured thereto. Then, the assembly of oil pumpand compressor may be bolted to the lower section and the connectionbetween the drive shaft 45 and coupling 46 may be made, working fromabove. Also, the shutter |89 may be assembled and connected to itsadjusting screw. Then, the upper section 4 may be put in place andsecured by the two screws l5. The top of the housing is then closed byfastening the transformer and control box 22 to the top of the uppersection d by means of two screws 23. This leaves the opening in the endwall 4 of the housing and, through this opening, is passed the assemblyof atomizing nozzle, electrodes, tube [15, primary air and oil pipes,the oil valve, oil-valveactuating means, primary air regulating valveland closure disk. When this unit is pushed into the housing and tube i6, the tube |75 will` engage the inner peripheral edges of theturbulator vanes 114, whereby the tube and nozzle will be supported inproper coaxial relation with tube i6. The connection between theignition electrodes and the high tension terminals of the ignitiontransformer will be automatically made by the cams 135 engaging thespring-pressed plungers |86 during the. last stage of inward movement ofthe unit. The closure disk llwill nally t into and close the opening inwall i4, after which the screws I8 are applied to fasten disk l'l inplace and the assembly is complete.

It will be clear that the burner is readily disassembled for servicing.By removing screws I8 and disconnecting the air and oil pipes 53 and|519 at their unions H8 and l E9, respectively, the disk I'l may beremoved, carrying with it as one unit, the atomizing nozzle, ignitionelectrodes, tube H5, oil valve, oil and primary air pipes, oil-valveactuating means and primary air regulating means. All these parts may beremoved without disturbing their cooperative relationship. If the partsof this unit are disassembled, they may be replaced in the desiredrelationship before the unit is replaced and such relationship will beretained during the replacement of the unit. The connections between theignition electrodes and transformer terminals are automatically brokenand made as the described unit is respectively withdrawn and replaced.After the described unit hasr been withdrawn, the upper section 4 may beremoved to give full access to the fan and fan housing for cleaning.

The invention thus provides an improved oil burner of the air-atomizingtype, which is capable of manufacture at relatively low cost and yetprovides for clean and efficient combustion under conditions that areaccurately regulable, and which provides for convenient assembling anddisassembling of parts and for convenient adjustment of ow rates andpressure of the air and oil.

What is claimed is:

l. In an air-atomizing oil. burner, of the type wherein oil and primaryair are respectively supplied through inner and outer coaxial pipes toan air-atomizing nozzle, fixed to the outer ends of said pipes andlocated in one end of an openended draft tube through which secondaryair is supplied to mix with the atomized oil emitted from said nozzleand wherein the flow of oil to said nozzle is controlled by a valvelocated in the inner pipe near the nozzle and having a rod extendingthrough such pipe and xed to a diaphragm actuated in one direction bypressure of the primary air and in the other direction by a spring; aclosure for the otherend of said tube having a recess in its inner face,a member located within said tube having a recess in its outer face andto which member the inner ends of said pipes are connected, said closureand member being ii-xed together and clamping between them the marginalportion of said diaphragm, the inner portion of the diaphragm separatingsaid recesses one from another, said spring being located in the recessin said closure, said member having a supply passage for primary aircommunicating with the inner end of saidv outer pipe and with the recessin said member and an oil supply passage communicating with the innerend of said inner pipe,l and a spring-closed relief valve adapted toopen on excess pressure of the primary air, said relief valve and itsspring being mounted in said member, the latter having a passageconnecting said air-supply passage to one side of said relief valve anda vent passage connecting the other side of said relief valve to thespace within said draft tube.

2. An air-atomizing burner, as claimed in claim l, having meansaccessible from outside said draft tube for adjusting the pressure ofboth valve springs the one independently of the other.

HARRY F. TAPP. RICHARD NI. COCHRANE.

References Cited in the iilev of this patent UNITED STATES PATENTSNumber Name Date 1,287,253 Discher Dec. l0, 1918 1,640,728 Scott Aug.30, 1927 1,716,244 Sager June 4, 1929 1,716,325 Rogers June 4, 19292,489,823 Senninger Nov. 29, 1949

